In the past, throttle bodies have been used for metering a fluid flow in an internal combustion engine. Typically, these throttle bodies include a butterfly valve member which is rotationally positioned in an intake bore. The valve member is rotationally coupled to the valve body by way of one or more bearings.
Because the valve is positioned in the intake portion of the valve body, a pressure differential or delta exists between the high-pressure side of the butterfly valve and the low-pressure side of the butterfly valve. Also, a pressure differential or delta exists between the inboard side of the shaft bearing that is nearer to the valve than the outboard side of the shaft bearing. The result of these pressure differentials or deltas is that it can force contaminants into the bearing as well as force lubricant out of the bearing.
Typically, it has been attempted to provide an extremely low tolerance seal to reduce these tendencies. However, needing to engineer the seal to such low tolerances increases the cost of the assembly and is typically not effective in reducing the previously described problems with the bearings. These problems are particularly troublesome in turbocharged or boosted engines having higher pressure than normally aspirated engines.
Accordingly, there exists a need for a new and improved fluid flow metering system, and method of operating the same, in order to overcome the aforementioned deficiencies. Additionally, there exists a need for a new and improved throttle body, and method of operating the same, in order to overcome the aforementioned deficiencies. Furthermore, there exists a need for a new and improved bearing system and method of operating the same, in order to overcome the aforementioned deficiencies.